<!doctype html>
<title>CSS Shadow Parts - Pseudo class and exported parts</title>
<link rel="help" href="https://drafts.csswg.org/css-shadow-parts" >
<link rel="help" href="https://drafts.csswg.org/selectors/#matches">
<link href="https://drafts.csswg.org/selectors/#matches" rel="help">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-actions.js"></script>
<script src="/resources/testdriver-vendor.js"></script>
<style>
/* NOTE: Even though it might be tempting to use :focus instead, because we
   can more easily add that state programmatically, that'd defeat the point
   of the test, since :focus / :focus-visible has default styles which
   invalidate the element's style anyways */
#host::part(a):hover {
  background: blue;
}
</style>
<div id="host"></div>
<script>
let host = document.querySelector('#host')
host.attachShadow({mode: 'open'}).innerHTML = `<div part="b" exportparts="a"></div>`;

let innerHost = host.shadowRoot.querySelector('div');
innerHost.attachShadow({mode: 'open'}).innerHTML = `
  <style>
    div {
      width: 100px;
      height: 100px;
      background: black;
      color: white;
    }
  </style>
  <div part="a">hover, the background should be blue</div>
`;

let part = innerHost.shadowRoot.querySelector("div");
let t = async_test("Invalidation of nested part on hover");
part.addEventListener("mouseover", t.step_func_done(function() {
  assert_true(part.matches(":hover"), "Element should be hovered");
  assert_equals(getComputedStyle(part).backgroundColor, "rgb(0, 0, 255)", "Hover style should apply");
}));

new test_driver.Actions()
    .pointerMove(0, 0)
    .pointerMove(50, 50)
    .send();
</script>
